1. Field of the Invention
This invention relates to a hydraulic brake control assembly for automotive vehicles, and more particularly to a brake pressure control assembly responsive to vehicle deceleration.
2. Description of the Prior Art
Generally, it is well known that vehicle deceleration is proportional to the hydraulic brake pressure and that the hydraulic brake pressure, in order to obtain a certain deceleration, is varied according to the loading conditions of the vehicle, i.e., the brake pressure necessary to obtain a certain deceleration at the minimum vehicle load is smaller than the brake pressure necessary to obtain the deceleration at the maximum vehicle load. That is to say as the vehicle load increases the hydraulic pressure necessary for braking must also increase.
In addition, it is also well known that it is desirable to actuate a proportioning valve in accordance with the vehicle loading, i.e., it is desirable to actuate the proportioning valve at the greater hydraulic pressure when the vehicle load is large than when the vehicle load is small. That is to say, as the vehicle load increases the hydraulic pressure suitable for actuating the proportioning valve must also increase.
There have been proposed various means to utilize a hydraulic pressure value for obtaining the starting point of actuation of the proportioning valve i.e., the deflecting point corresponding to the hydraulic pressure value for obtaining a certain vehicle deceleration. However, it should be noted that merely sensing of the vehicle deceleration is insufficient because the variance in the deflecting point of the proportioning valve is of too small a range to actuate the proportioning valve. Therefore, conventional means have not been completely satisfactory for accomplishing the primary purpose since they have been too complicated in structure or not reliable in operation.